Mesh networks
Wireless mesh networks Background 802.11 based Wireless LANs (WLANs) have become a pervasive technology in modern day communication infrastructure. In a WLAN, a wireless access point (AP) serves clients in a given area. The AP has wired connectivity, thereby providing internet access to users, via one wireless hop. However, in order to cover an extended area, each AP would have to be wired to the backbone, which significantly drives up the cost of deploying WLANs. Motivated by this limitation, Wireless mesh networks wree proposed as a solution. Introduction Wireless mesh networks (WMNs) are rapidly emerging as low-cost and flexible alternatives for wired infrastructure networks. WMN's work by creating a multi-hop backbone which can be used to extend limited infrasructure network, interconnecting isolated LANs and providing backhaul access to users. Recently, WMN's have become quite pervasive in the wireless market with several commercial projects in operation around the world. Examples are RoofNet at MIT, VMesh in Greece, MeshNet at UCSB, CUWiN in Urbana, Microsoft MESH, Google Mesh, ReMesh in Sao Paulo, Brazil, among others. Several enterprise solutions are also offered by companies like Nortel and Cisco. Network management for WMNs Challenges Managing WMNs is a significantly harder task than managing wired networks. Due to multi-hop nature of WMNs; they have limited bandwidth and traditional network management protocols like SNMP, Cisco's NetFlow and others, place a high overhead cost on the network. Also of importance, is the issue of failsafe update of key network parameters like essid or radio channel transmission power in WMNs to prevent network fragmentation. Conventional routine network management tasks such as IP configuration, security and network resource provisioning are exacerbated by the unique properties of WMNs like nodal mobility, dynamic network membership and unstable links. Objectives To provide a sufficient level of performance at par with their wired counterparts, network management tools for WMN's should meet certain performance criteria, such as: * Low user interaction: Performance management of the network shouldn't adversely affect current user traffic. * Reliability: Tools must have the ability to configure multiple parameters in one single block of command and fall back to a failsafe mode if something goes wrong. * Low disk/runtime footprint: Embedded devices like nodes in mesh backhaul will have limited memory. Management tools (specifically agent daemon running on host machine) should use as little permanent storage space and main memory space as possible. * Failure resilience: Tools should have the capability to deal with some nodes becoming inaccessible during the configuration process. Tools for managing WMNs Network initialization As in wired networks certain industry standards have started emerging in the use of management tools for WMN's. OpenWRT a Linux distribution for static embedded devices has emerged as the OS of choice for network administrators to implement network initialization in mesh routers. The relative ease of compiling separate OS images for each device and abundant tools for morphing each router to perform as a gateway or as a generic backhaul node have greatly factored in its acceptance. Network reconfiguration Most common functionality demanded by most network managers is the ability to apply new configuration parameters to all routers or to a subset at once. MAYA , a tool developed by researchers in university of Spain, attempts to address this issue with a GUI integrated with an OpenWRT configuration webpage. Critical network parameters like router MIB's and node ESSID can be updated with only a few clicks. Another method gaining traction is the use of a variation of Broadcast and copy shell (Bcp shell) that takes a string of commands as input and then broadcasts them to be executed in the terminals of separate nodes. Network security To prevent client side attacks on WMNs, user authentication and control are a vital part of network management framework.Captive portal solutions like WiFiDog, Coova and PatronSoft have gained widespread acceptance among network management community. A captive portal works as a combination of network firewall and webpage which restricts access to the network until the user completes the authentication process. An alternative method used by developers of MAYA, involves using SSH connection enabled routers. To complete configuration tasks using this software, network managers have to log themselves using a public key and a password. Network monitoring and statistics Network monitoring and statistics collection is an important tool for network diagnosis. Multi Router Traffic Grapher (MRTG) uses the widely deployed network monitoring tool on the internet. MRTG uses SNMP to poll traffic information from routers and generates HTML pages containing graphical images which provide a live representation of the traffic. Active measurements of the system can be supported by the well known tools like ping ''and ''iperf ''during a short period. See also * IETF draft on network management of Mobile ad-hoc networks * [http://trilug.org/~bfarrow/talks/iperf-Bill-Farrow-2013.pdf Introductory slides on network testing using ''iperf]'' '' * Nortel mesh network at MIT Media Labs References #Wireless Mesh Networks Wiki # MAYA: Tool for wirless mesh network management, IEEE international conference on Mobile ad-hoc and sensor networks, MASS 2007 # Cognitive network management for wireless mesh networks # Management issues in wireless mesh networks # Managing Wireless Mesh Networks: Measurement-based Approach # Routing and bandwidth management for Wireless Mesh Networks using ant intelligence # Cisco Wireless Mesh Access Points, Design and Deployment Guide, Release 7.0 # OpenWRT: Linux distribution for embedded devices # WiFiDog: A captive portal suite